• Florian Westphal's avatar
    [Syncookies]: Add support for TCP options via timestamps. · 4dfc2817
    Florian Westphal authored
    Allow the use of SACK and window scaling when syncookies are used
    and the client supports tcp timestamps. Options are encoded into
    the timestamp sent in the syn-ack and restored from the timestamp
    echo when the ack is received.
    
    Based on earlier work by Glenn Griffin.
    This patch avoids increasing the size of structs by encoding TCP
    options into the least significant bits of the timestamp and
    by not using any 'timestamp offset'.
    
    The downside is that the timestamp sent in the packet after the synack
    will increase by several seconds.
    
    changes since v1:
     don't duplicate timestamp echo decoding function, put it into ipv4/syncookie.c
     and have ipv6/syncookies.c use it.
     Feedback from Glenn Griffin: fix line indented with spaces, kill redundant if ()
    Reviewed-by: default avatarHagen Paul Pfeifer <hagen@jauu.net>
    Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    4dfc2817
tcp.h 39.8 KB